[27] Am. Jour. Sci., 3d series, Vol. XXVI, 1883, pp. 222-235.
[28] Neues Jahrbuch für Min., etc., Vol. I, 1885, pp. 222-226.
[29] Observed by Iddings: Twelfth Ann. Rept. U. S. Geol. Survey, p. 612.
[30] Hague and Iddings: Twelfth Ann. Rept. U. S. Geol. Survey, p. 225.
[31] Oebbeke, op. cit., p. 226.
[32] Jour. Geol., Vol. IV, 1896, p. 276.
[33] Emmons, Bull. Am. Geog. Soc., 1877, No. 4, p. 45.
Transcriber's Note:
Obvious typographical errors were corrected. Hyphenation variants present in the original were retained.
Author/subject illustrations have been re-positioned to the beginning of chapters to which they pertain.